1. Field of the Invention
The present invention relates to context aware technology, and more particularly, to a context aware system and a context aware method thereof, which manage facts and rules necessary for context awareness according to constraints in ubiquitous environments, thereby reasoning service contexts.
The present invention was supported by the IT R&D program of MIC/IITA[2006-S007-02, Ubiquitous Health Monitoring Module and System Development].
2. Description of the Related Art
Context aware technology in ubiquitous environments is being utilized to recognize contexts and discern services in order to provide a desired service based upon sensor data acquired from users, peripheral devices and surrounding environments.
In general, context aware systems have a large amount of context information and rules for contextual inference, and make a inference through reasoning. The more the context information and the rules are used in the reasoning, the longer reasoning time may be. The increased reasoning time acts as an obstacle against real-time processing.
However, in actual service environments, data is delivered in real-time from a sensor surrounding a user, and contextual inference also requires real-time processing. Thus, real-time processing is an essential factor in the context aware service.
In order to ensure real-time processing, it is required to complement a reasoning method. reasoning methods based upon ontologies, as an attempt to enhance reasoning speed, use cashing methods for rules and contexts, or reducing the number of rules stored in a memory in a processing time by organizing an ontology into a upper level ontology, which is domain-independent, and a lower level ontology, which is domain-dependent. In particular, conventional technologies have attempted to improve speed by reducing the number of context information used in reasoning. That is, a context aware application analyzes queries to be used in the context awareness, so that only context information associated with the queries is stored in the working memory in real-time. In the meantime, ubiquitous data generally include spatial components and temporal components. The spatial components and the temporal components are included in context information, which can be filtered with respect to the spatial and temporal components since the conventional technologies do not consider neither the spatial components nor the temporal components. Accordingly, there is still a large amount of data to be processed.